Anura (frogs and toads) is the most diverse extant order of the Amphibia, with 7,627 species, 446 genera, and up to 55 families (88% of all extant amphibian species as of June 2023). Currently the families richest in species are the Hylidae (973 spp.), Strabomantidae (673), Microhylidae (606), and Bufonidae (607); formerly over 1,100 species were included in the Leptodactylidae, which has been since split up. Limits of some of the anuran families are still debated.

The anurans are short-bodied and tailless, usually with smooth, moist, semi-permeable skins, making them susceptible to dehydration; species living in less humid environments may have drier glandular skin. Although most species lay their eggs in water, many enter aquatic environment only during the short breeding cycle and spend the rest of the year in terrestrial, arboreal or subterranean habitats. The eggs hatch into aquatic larvae called tadpoles which have tails and internal gills; the tadpoles metamorphose into adults. Many terrestrial species deposit eggs in moist sites on land and bypass the tadpole stage entirely, i.e., the larvae undergo their development within the egg membranes and emerge as tiny froglets.

Anurans are widely distributed, occurring from below sea level up to 4,600 metres. The greatest diversity is found in the humid tropical forests, especially in the Atlantic Forest of Brazil, the Andes of Colombia, Peru, and Ecuador, the Amazon Basin, Equatorial Africa, and Madagascar.

Many frog populations have declined significantly since the 1950s. More than one third of species are considered to be threatened with extinction, and over one hundred and twenty species may have become extinct since the 1980s, e.g., though the rise of an emerging fungal disease. Most severe declines occurred in Central America.

Photos of frogs and toads are temporarily offline. Please check the "Amphibian Species in Our Collection" page for available images. This page will be rebuilt in late 2017, but we could upload species upon inquiry.